This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 10-129026, filed May 12, 1998, the entire contents of which are incorporated herein by reference.
The present invention relates to a cigarette filter wrapper paper, cigarette filter and filter-tipped cigarette.
Recently, a tendency of favoring mild tobacco taste for tobacco products such as cigarettes has become increasingly stronger. To obtain mild tobacco taste, there are known a technique of expanding cut tobacco itself used for a cigarette to make the flavor or taste milder, and a technique of fitting a filter to the end of tobacco column of a cigarette.
In the latter technique of fitting the filter, in order to make tobacco flavor and taste still milder, it has been a practice that a filter body is composed of a plurality of filter sections, such as a so-called dual-filter, and activated carbon or the like is dispersed into the filter section constituting the mouth end portion. In addition, it has also been a practice that many ventilation holes are circumferentially made in a so-called tip paper which connects the filter body to the tobacco column integrally. The taste of the cigarette can be made milder by ambient air sucked through the ventilation holes when smoked. Furthermore, as a filter wrapper for wrapping a filter body, a paper sheet having a higher air permeability is also used.
However, when a filter wrapper having a high permeability is used, it may result in trouble while wrapping the filter plug since the strength of such a filter wrapper having a high permeability is low. Also, when such a filter wrapper is glued, the glue exudes from the filter wrapper to the conveyer belt, thus making it difficult to wrap filter plugs continuously. Further, when manufacturing a filter-tipped cigarette, a filter plug is sent to a cigarette-making machine by airblow. Here, when a filter wrapper having a high permeability is used, glue exudes out in the air blower unit for the filter plug, and the exuded-out glue is attached to an inside of the air blower unit. Later on, it peals off, and mixes into the filter plug, thus making it difficult to continuously make cigarettes.
Therefore, an object of the present invention is to provide a cigarette filter wrapper which can suppress the exudation of glue so as to be able to continuously make filter-tipped cigarettes without difficulties, and also can achieve a high ventilation rate.
Another object of the present invention is to provide a cigarette filter wrapped by such a cigarette filter wrapper.
Still another object of the present invention is to provide a cigarette having such a cigarette filter.
According to a first aspect of the present invention, there is provided a cigarette filter wrapper paper comprising a plurality of layers or plies which are integrally combined together and having a first surface and a second surface, the filter wrapper paper exhibiting a first overlap air permeability, measured when a perforated tip paper is overlapped on the first surface, and a second overlap air permeability, measured when a perforated tip paper is overlapped on the second surface, the first overlap air permeability being higher than the second overlap air permeability.
In the present invention, it is preferable that the first overlap air permeability should be 1.5 times or more higher than the second overlap air permeability.
In the present invention, it is desirable that the layer or ply which provides the first surface should have a single-layer air permeability of, preferably, 10,000 CORESTA units or more, and more preferably, 30,000 CORESTA units or more, and the layer or ply which provides the second surface should have a single-layer air permeability lower than that of the layer which provides the first surface, in a range of, preferably, 1800 to 2,5000 CORESTA units.
In the present invention, the layer or ply which provides the first surface should preferably have a single-layer thickness of 30 to 100 xcexcm, and the layer or ply which provides the second surface should preferably have a single-layer thickness of 15 to 35 xcexcm.
Further, the wrapper paper of the present invention should preferably have a total air permeability of 1500 to 15000 CORESTA units, and should preferably have a total thickness of 40 to 130 xcexcm.
According to the second aspect of the present invention, there is provided a cigarette filter wrapping paper comprising a paper sheet having a first surface and a second surface, the filter wrapper paper exhibiting a first overlap air permeability, measured when a perforated tip paper is overlapped on the first surface, and a second overlap air permeability, measured when a perforated tip paper is overlapped on the second surface, the first overlap air permeability being 1.5 times or more higher than the second overlap air permeability.
According to the third aspect of the present invention, there is provided a cigarette filter wrapped by the wrapper paper of the present invention such that the first surface of the wrapper paper faces outwards.
According to the fourth aspect of the present invention, there is provided a filter-tipped cigarette comprising a tobacco portion and a filter portion which are connected to each other with a tip paper having a plurality of ventilation holes, the filter-tipped cigarette having a filter section wrapped (directly or indirectly) by the wrapper paper of the present invention disposed such that the first surface faces outwards, at a position corresponding to the ventilation holes.
In the present invention, the overlap air permeability refers to an air permeability when air is allowed to pass through the wrapper paper from a perforated tip paper overlaid on the wrapper paper.
In the present invention, the single-layer air permeability refers to an air permeability of each individual sheet of paper when the layers which constitute wrapper paper are individually formed into individual single sheets, respectively, without combining them with each other. Further, in the present invention, the single-layer thickness refers to a thickness of each individual sheet when the layers which constitute wrapper paper are individually formed into individual single sheets, respectively, without combining them with each other.
In the present invention, the total air permeability of the wrapper paper refers to an air permeability of the entire wrapper paper measured without overlaying tip paper.
In the present invention, the first surface and the second surface of the wrapper paper refers to the two surfaces of the wrapper paper, extending in the direction intersecting the thickness direction of the wrapper paper.
In the present invention, any of the air permeability values are measured in accordance with the method specified in ISO 2965.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.